In general the leather is produced in the following grades (at Urban Krafts we use full-grain leather to make our belts).
Top-grain leather includes the outer layer of the hide, known as the grain, which features finer, more densely packed fibers, resulting in strength and durability. Depending on thickness, it may also contain some of the more fibrous under layer, known as the corium. Types of top-grain leather include:
Full-grain leather contains the entire grain layer, without any removal of the surface. Rather than wearing out, it develops a patina during its useful lifetime. It is considered the highest quality leather and we use it for our belts at Urban Krafts. Furniture and footwear are often made from full-grain leather.
You can find this belt in our store at www.urbankrafts.com, which is made with 100% full grain leather.
Corrected grain leather has the surface subjected to finishing treatments to create a more uniform appearance. This usually involves buffing or sanding away flaws in the grain, then dyeing and embossing the surface.
Example of corrected grain leather (source from google)
Nubuck is top-grain leather that has been sanded or buffed on the grain side to give a slight nap of short protein fibers, producing a velvet-like surface.
Example of nubuck leather (source from google)
Split leather is created from the corium left once the top-grain has been separated from the hide, known as the drop split. In thicker hides, the drop split can be further split into a middle split and a flesh split. Splits are often used to create suede. Split leather can also have a polyurethane or vinyl layer applied to the surface and embossed to give it the appearance of a grain, known as bicast leather, which is slightly stiffer than top-grain leather but has a more consistent texture.
Patent leather is leather that has been given a high-gloss finish by the addition of a coating. Inventor Seth Boyden developed the first mass-production process, using a linseed oil-based lacquer, in Newark, New Jersey, in 1818. Modern versions usually have a plastic coating, similar to bicast leather.
Bonded leather, also called reconstituted leather, is a material that uses leather scraps that are shredded and bonded together with polyurethane or latex on to a fiber mesh. The amount of leather fibers in the mix varies from 10% to 90%, affecting the properties of the product.
Content taken from wikipedia and other public sources.